1. Field of Invention
The present invention relates to immobilised supported polymerisation catalysts for atom transfer polymerisation of olefinically unsaturated monomers in which molecular weight control is achieved by the presence of certain transition metal, especially copper, complexes.
2. Description of Related Art
It is desirable to be able to produce high molecular weight polymers with a low molecular weight distribution by catalysed addition polymerisation, in particular of vinylic monomers. Hitherto this has been achieved by polymerising via ionic processes typically in the presence of organometallics such as alkyl lithiums which are sensitive as regards reaction with water and other protic species. As such, monomers containing functional groups are not readily polymerised. The use of ionic systems also precludes the use of solvents which contain protic groups and/or impurities resulting in very stringent reaction conditions and reagent purity being employed.
More recently atom transfer polymerisation based on the combination of a transition metal halide and alkyl halide have been utilised. For example, Matyjasewski (Macromolecules (1995), vol. 28, pages 7901-7910 and WO96/30421) has described the use of CuX (where X=Cl, Br) in conjunction with bipyridine and an alkyl halide to give polymers of narrow molecular weight distribution and controlled molecular weight. This system suffers from the disadvantage that the copper catalyst is partially soluble in the system and thus a mixture of homogeneous and heterogeneous polymerisation ensues. The level of catalyst which is active in solution is thus difficult to determine. The catalyst residues which are soluble in the reaction medium prove difficult to remove from the product. Percec (Macromolecules, (1995), vol. 28, page 1995) has extended Matyjasewski""s work by utilising arenesulphonyl chlorides to replace alkyl chlorides, again this results in a mixture of homogeneous and heterogeneous polymerisation and catalyst residues are difficult to remove from the product. Sawamoto (Macromolecules, (1995), vol. 28, page 1721 and Macromolecules, (1997), vol. 30, page 2244) has also utilised a ruthenium based system for similar polymerisation of methacrylates. This system requires activation of monomer by an aluminum alkyl in order to achieve the best results, itself sensitive to reaction with protic species which is an inherent disadvantage. These systems have been described as proceeding via a free radical mechanism which suffers from the problem that the rate of termination is  greater than 0 due to normal radical-radical combination and disproportionation reactions.
The inventors have found that the use of diimines such as 1,4-diaza-1,3-butadienes and 2-pyridinecarbaldehyde imines may be used in place of bipyridines. These ligands offer the advantage of homogeneous polymerisation and thus the level of active catalyst can be accurately controlled and only one polymerisation process ensues. This class of ligand also enables the control of the relative stability of the transition metal valencies, for example, Cu(I) and Cu(II), by altering ancillary substituents and thus gives control over the nature of the products through control over the appropriate chemical equilibrium. Such a system is tolerant to trace impurities, trace levels of O2 and functional monomers, and may even be conducted in aqueous media. This system is the subject of copending patent application number PCT/GB97/01587.
A further advantage of this system is that the presence of free-radical inhibitors traditionally used to inhibit polymerisation of commercial monomers in storage, such as 2,6-di-tert-butyl-4-methylphenol (topanol), increases the rate of reaction of the invention. This means that lengthy purification of commercial monomers to remove such radical inhibitors is not required. Furthermore, this indicates that the system is not a free-radical process. This is contrary to Matajaszewski and Sawamoto who show free-radical based systems.
A difficulty identified by the inventors for the commercialisation of the radical polymerisation system of Matajazewski and Sawamoto, and the diimine-based system described above is that high levels of catalysts are required for acceptable rates of polymerisation. This means that catalyst is relatively expensive as it is not recycled/reused and it must be removed by lengthy procedures to prevent contamination of the final product and to keep production costs down.
The inventors have therefore identified a process for attaching the catalyst to supports which allows the catalyst to be easily recovered and produces products with substantially less contamination than previously described systems.
Such supported catalysts were expected by the inventors to clump together since each metal ion can coordinate with two-ligands, each of which is attached to a support. This would reduce the effectiveness of such supported systems. However, this has not been observed by the inventors. Furthermore, the metal ion is tightly bound to the ligands and does not leach off into the surrounding solution or product, allowing it to be reused.
A first aspect of the invention provides a supported ligand for use in catalysts for polymerisation of olefinically unsaturated monomers, especially vinylic monomers, said ligand being one or more compounds attached to a support.
Such a ligand has general formula:
S(D)nxe2x80x83xe2x80x83FORMULA 1
where:
S is the support,
D is a compound attached to the support, said compound being capable of complexing with a transition metal, and
n is an integer of one or more.
Preferably, the support is inorganic, such as silica, especially silica gel. Alternatively the support may be organic, especially an organic polymer, especially a cross-linked organic polymer, such as poly(styrene-w-divinylbenzone). Preferably the support is in the form of beads. This latter form is particularly advantageous because it has a high surface area which allows the attachment of a large number of compounds, whilst presenting a large surface area to the medium to be catalysed.
The compound (D) may be adsorbed onto the support or covalently attached to the support.
Preferably the compound is an organic compound comprising Schiff base, amine, hydroxyl, phosphine or diimine capable of complexing with a transition metal ion. Each Schiff base, amine, hydroxyl, phosphine or diimine is preferably separated from the support by a branched or straight alkyl chain, especially a chain containing 1 to 20 carbon atoms. The chain may comprise one or more aromatic groups as part of the alkyl chain.
One preferred ligand is the use of a support attached to two or more alkyl-amines, such as aminopropyl-, aminobutyl-, aminopentyl-, aminohexyl-, aminoheptyl- or aminooctyl-functionalised support. The amine groups are capable of forming a complex with one or more transition metal ions.
Especially preferred compounds are diimines.
Preferably one of the nitrogens of the diimine is not part of an aromatic ring.
Preferably the diimine is a 1,4-diaza-1,3-butadiene 
where R1, R2, R10, R11, R12 and R13 may be varied independently and R1, R2, R10, R11, R12 and R13 may be H, straight chain, branched chain or cyclic saturated alkyl, hydroxyalkyl, carboxyalkyl, aryl (such as phenyl or phenyl substituted where substitution is as described for R4 to R9), CH2Ar (where Ar=aryl or substituted aryl) or a halogen. Preferably R1, R2, R10, R11, R12 and R13 may be a C1 to C20 alkyl, hydroxyalkyl or carboxyalkyl, in particular C1 to C4 alkyl, especially methyl or ethyl, n-propylisopropyl, n-butyl, sec-butyl, tent-butyl, cyclohexyl, 2-ethylhexyl, octyl, decyl or lauryl. R1, R2, R10, R11, R12 and R13 may especially be methyl.
R3 to R9 may independently be selected from the group described for R1, R2, R10, R11, R12 and R13 or additionally OCnH2n+1, (where n is an integer from 1 to 20), NO2, CN or Oxe2x95x90CR (where R=alkyl, benzyl PhCH2 or a substituted benzyl, preferably a C1 to C20 alkyl, especially a C1 to C4 alkyl).
Furthermore, the compounds may exhibit a chiral centre xcex1 to one of the nitrogen groups. This allows the possibility for polymers having different stereochemistry structures to be produced.
Compounds of general Formula 3 may comprise one or more fused rings on the pyridine group.
One or more adjacent R1 and R3, R3 and R4, R4 and R2, R10 and R9, R8 and R9, R8 and R7, R7 and R6, R6 and R5 groups may be C5 to C8 cycloalkyl, cycloalkenyl, polycycloalkyl, polycycloalkenyl or cyclicaryl, such as cyclohexyl, cyclohexenyl or norborneyl.
The diimine compounds are preferably covalently attached to the support via positions R1, R2, R9, R10, R11, R12 or R13. They maybe attached via a linkage group, such as a Schiff base to the support.
Preferred diimines include: 
where: * indicates a chiral centre.
R14=Hydrogen, C1 to C10 branched chain alkyl, carboxy- or hydroxy-C1 to C10 alkyl.
The ligands, according to the first aspect of the invention, may be used to from a catalyst for the addition polymerization of olefinically unsaturated monomers by using them in conjunction with:
a) a compound of formula 30
xe2x80x83MY
where M is a transition metal in a low valency state or a transition metal in a low valency state co-ordinated to at least one co-ordinating non-charged ligand and Y is a monovalent or polyvalent counterion; and
b) an initiator compound comprising a homolytically cleavable bond with a halogen atom.
Homolytically cleavable means a bond which breaks without integral charge formation on either atom by homolytic fission. Conventionally this produces a radical on the compound and a halogen atom radical. For example: 
However, the increase in the rate of reaction observed by the inventors with free-radical inhibitor indicates that true free-radicals are not necessarily formed using the catalysts of the invention. It is believed that this possibly occurs in a concerted fashion whereby the monomer is inserted into the bond without formation of a discrete free radical species in the system. That is during propagation this results in the formation at a new carbon-carbon bond and a new carbon-halogen bond without free-radical formation. The mechanism possibly involves bridging halogen atoms such as: 
where:
ML is a transition metal-diimine complex.
A xe2x80x9cfree-radicalxe2x80x9d is defined as an atom or group of atoms having an unpaired valence electron and which is a separate entity without other interactions.
Transition metals may have different valencies, for example Fe(II) and Fe(III), Cu(I) and Cu(II), a low valency state is the lower of the commonly occurring valencies, i.e. Fe(II) or Cu(I). Hence M in Formula 30 is preferably Cu(I), Fe(II), Co(II), Ru(II), Rh(I) or Ni(II), most preferably Cu(I). Preferably the coordinating ligand is (CH3CN)4. Y may be chosen from Cl, Br, F, I, NO3, PF6, BF4, SO4, CN, SPh, SCN, SePh or triflate (CF3SO3). Copper (I) triflate may be, which may be in the form of a commercially available benzene complex (CF3SO3Cu)2C6H6. The especially preferred compound used is CuBr.
Preferably the second component (b) is selected from:

where R is independently selectable and is selected from straight, branched or cyclic alkyl, hydrogen, substituted alkyl, hydroxyalkyl, carboxyalkyl or substituted benzyl. Preferably the or each alkyl, hydroxyalkyl or carboxyalkyl contains 1 to 20, especially 1 to 5 carbon atoms.
X is a halide, especially I, Br, F or Cl.
The second component (b) may especially be selected from Formulae 43 to 52: 
where:
X=Br, I or Cl, preferably Br
Rxe2x80x2=xe2x80x94H,
xe2x80x94(CH2)pRxe2x80x3 (where m is a whole number, preferably p=1 to 20, more preferably 1 to 10, most preferably 1 to 5, Rxe2x80x3=H, OH, COOH, halide, NH2, SO3, COXxe2x80x94 where X is Br, I or C) or: 
R111=xe2x80x94COOH, xe2x80x94COX (where X is Br, I, F or Cl), xe2x80x94OH, xe2x80x94NH2 or xe2x80x94SO3H, especially 2-hydroxyethyl-2xe2x80x2-methyl-2xe2x80x2-bromopropionate. 
Especially preferred examples of Formula 45 are: 
Br may be used instead at Cl in Formulae 46A and 46B. 
The careful selection of functional alkyl halides allows the production of terminally functionalised polymers. For example, the selection of a hydroxy containing alkyl bromide allows the production of xcex1-hydroxy terminal polymers. This can be achieved without the need of protecting group chemistry.
The transition metal may be precoordinated to the ligand covalently attached to its support.
Accordingly a second aspect of the invention provides a catalyst for use in the addition polymerisation of olefinically unsaturated monomers; especially vinyl monomers comprising a compound of general formula:
[(SD)cM]d+Axe2x80x83xe2x80x83Formula 52
where:
M=a transition metal in a low valency state or a transition metal co-ordinated to at least one co-ordinating non-charged ligand,
S=a support,
D=a compound attached to the support, the compound being capable of complexing with a transition metal,
d=an integer of 1 or 2,
c=an integer of 1 or 2,
A=a monovalent or divalent counter ion, such as Cl, Br, F, I, NO3, PF6, BF4, SO4, CN, SPh.
Preferably M is a defined for Formula 30 above. S may be as defined for Formula 1.
D may be adsorbed or covalently attached to the support.
D may be a compound as described earlier for the first aspect of the invention.
D may have one of the nitrogens as not part of a diimine ring.
D may be a diimine according to Formulae 2-29 as previously defined.
Preferably the catalyst is used with an initiator comprising a homolytically cleavable bond with a halogen atom, as previously defined. Preferred initiators are those defined in the first aspect of the invention according to Formulae 31 to 53.
A third aspect of the invention provides a process for the production of compound such as diimine covalently attached to supports, according to the first or second aspects of the invention.
The invention provides a process for producing a ligand for use in the catalysis of addition polymerisation of olefinically unsaturated monomers, especially vinylic monomers, comprising the steps of:
(a) providing a primary amine functionalised support;
(b) providing a ligand precusor comprising an aldehyde group or ketone group; and
(c) reacting the primary amine functionalised support with the ligand precursor to form a diimine compound covalently attached to the support.
The primary amine of the functionalised support reacts with the aldehyde group or ketone group to form a Schiff base. Accordingly the diimine may be produced by providing a ligand precursor with an aldehyde or ketone group replacing one of the imine groups of the final product, the reaction with the primary amine producing the second imine group. This is shown in the reaction scheme below which shows the reaction of a support functionalised with a primary amine with 2-pyridine carbaldehyde to form a diimine attached to the support according to the first aspect of the invention. This can then be mixed with copper bromide or copper chloride to form a catalyst according to the second aspect of the invention. 
Alternatively an aldehyde or a ketone group may be provided separately on a diimine ligand precursor. Such a suitable precursor is shown in Formula 53 
This allows the diimine to be decoupled from the support to allow controlled polymerisation.
Alternatively the following reaction scheme may be followed: 
The primary amine group may alternatively be provided on the ligand precursor and reacted with a ketone or aldehyde functionalised support.
The support material may be functionalised inorganic material, such as silica, especially silica gel. Alternatively functionalised organic support, especially a functionalised cross-linked polymeric support, such as poly(styrene-w-divinylbenzene) may be used. Such supports are preferably usually used for absorbing compounds or in chromatography.
Preferably the reaction to form the Schiff base occurs at room temperature.
Preferably the functionalised support is an aminopropyl functional silica and the ligand precursor is 2-pyridine carbaldehyde.
The supported ligands and supported catalysts of the invention may be used in batch reactions or in continuous reactions to polymerise olefinically unsaturated monomers. In the latter case, the supported catalyst or ligand may be packed into columns and the reaction mixture passed through.
The supported ligand or supported catalyst may be conveniently removed from a reaction mixture by, for example, filtration, precipitation or centrifugation. Alternatively the support may be magnetised beads and the catalyst is removed by means of a magnet.
The invention also provides the use of the catalyst according to the first or second aspect of the invention in the addition polymerisation of one or more olefinically unsaturated monomers and the polymerised products of such processes.
The components may be used together in any order.
The inventors have unexpectedly found that the catalyst will work at a wide variety of temperatures, including room temperature and as low as xe2x88x9215xc2x0 C. Accordingly, preferably the catalyst is used at a temperature of xe2x88x9220xc2x0 C. to 200xc2x0 C., especially xe2x88x9220xc2x0 C. to 150xc2x0 C., 20xc2x0 C. to 130xc2x0 C., more preferably 90xc2x0 C.
The olefinically unsaturated monomer may be a methacrylic, an acrylate, a styrene, methacrylonitrile or a diene such as butadiene.
Examples of olefinically unsaturated monomers that may be polymerised include methyl methacrylate, vinylacetate, vinyl chloride acylonitonile, methacylamide, acrylamide, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), and other alkyl methacrylates; corresponding acrylates; also functionalised methacrylates and acrylates including glycidyl methacrylate, trimethoxsysilyl propyl methacrylate, allyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dialkylaminoalkyl methacrylates; fluoroalkyl (meth)acrylates; methacrylic acid, acrylic acid; fumaric acid (and esters), itaconic acid (and esters), maleic anhydride; styrene, xcex1-methyl styrene; vinyl halides such as vinyl chloride and vinyl fluoride; acrylonitrile, methacrylonitrile; vinylidene halides of formula CH2xe2x95x90C(Hal)2 where each halogen is independently Cl or F; optionally substituted butadienes of the formula CH2xe2x95x90C(R15)C(R15)xe2x95x90CH2 where R15 is independently H, C1 to C10 alkyl, Cl, or F; sulphonic acids or derivatives thereof of formula CH2xe2x95x90CHSO2OM wherein M is Na, K, Li, N(R16)4 where each R16 is independently H or C1 to C10 alkyl, D is COZ, ON, N(R16 )2 or SO2OZ and Z is H, Li, Na, K or N(R16)4; acrylamide or derivatives thereof of formula CH2xe2x95x90CHCON(R16)2; and methacryiamide or derivative thereof of formula CH2xe2x95x90C(CH3)CON(R16)2. Mixtures of such monomers may be used.
Preferably, the monomers are commercially available and may comprise a free-radical inhibitor such as 2,6-di-tert-butyl-4-methylpenol or methoxyplenol.
Preferably the co-catalysts are used in the ratios 0.01 to 1000 D: MY, preferably 0.1 to 10, and compound MY: initiator 0.0001 to 1000, preferably 0.1 to 10, where the degree of polymerisation is controlled by the ratio of monomer to (b) (expressed as molar ratios).
Preferably the components of the catalyst of the second aspect of the invention are added at a ratio M:initiator of 3:1 to 1:100.
Preferably the amount of diimine: metal used in the systems is between 1000:1 and 1:1, especially, 100:1 and 1:1, preferably 5:1 to 1:1, more preferably 3:1 to 1:1.
The ratio of RX:Copper is 1000:1 to 1:1, especially 100:1 to 1:1.
The reaction may take place with or without the presence of a solvent. Suitable solvents in which the catalyst, monomer and polymer product are sufficiently soluble for reactions to occur include water, protic and non-protic solvents including propionitrile, hexane, heptane, dimethoxyethane, diethoxyethane, tetrahydrofuran, ethylacetate, diethylether, N,N-dimethylformamide, anisole, acetonitrile, diphenylether, methylisobutyrate, butan-2-one, toluene and xylene. Especially preferred solvents are xylene and toluene, preferably the solvents are used at at least 1% by weight, more preferably at least 10% by weight.
Preferably the concentration of monomer in the solvents is 100% to 1%, preferably 100% to 5%.
The reaction may be undertaken under an inert atmosphere such as nitrogen or argon.
The reaction may be carried out in suspension, emulsion, mini-emulsion or in a dispersion.
Statistical copolymers may be produced using the catalysts according to the invention. Such copolymers may use 2 or more monomers in a range of ca.0-100% by weight of each of the monomers used.
Block copolymers may also be prepared by sequential addition of monomers to the reaction catalyst.
Telechelic polymers, may be produced using catalysts of the invention. For example, a functional initiator such as Formula 21 may be used with transformation of the w-Br group to a functional group such as xe2x80x94OH or xe2x80x94CO2H via use of a suitable reactant such as sodium azide.
Comb and graft copolymers may be produced using the catalysts of the invention to allow, for example, polymers having functional side chains to be produced, by use of suitable reagents.